Every time a village gets attacked its silver increases dramatically, even if attacked by 100 man unarmed army. Most somewhere between 5K to 16K silver up from 1K. But then when it gets attacked a second time it gets a huge upswing - New Bulugur is being attacked for a second time and so now has 49,000 silver.
Since this is a huge windfall to whoever takes these villages, its a bug (admittedly the gear will be slightly better but still -2) that can be abused ad nauseum - just keep attacking same village with 100 man unarmed armies to get gold count to hundreds of thousands and then attack with 500 man army to beat the 200 troops and get all the silver.